scholarly journals Linkage between the temporal and spatial variability of dissolved organic matter and whole-stream metabolism

2013 ◽  
Vol 10 (8) ◽  
pp. 5555-5569 ◽  
Author(s):  
S. Halbedel ◽  
O. Büttner ◽  
M. Weitere
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Primary Production ◽  
Gross Primary Production ◽  
Complex Structure ◽  
Low Molecular Weight ◽  
Stream Metabolism ◽  
Temporal And Spatial ◽  
Dom Composition

Abstract. Dissolved organic matter (DOM) is an important resource for microbes, thus affecting whole-stream metabolism. However, the factors influencing its chemical composition and thereby also its bio-availability are complex and not thoroughly understood. It was hypothesized that whole-stream metabolism is linked to DOM composition and that the coupling of both is influenced by seasonality and different land-use types. We tested this hypothesis in a comparative study on two pristine forestry streams and two non-forestry streams. The investigated streams were located in the Harz Mountains (central Europe, Germany). The metabolic rate was measured with a classical two-station oxygen change technique and the variability of DOM with fluorescence spectroscopy. All streams were clearly net heterotrophic, whereby non-forestry streams showed a higher primary production, which was correlated to irradiance and phosphorus concentration. We detected three CDOM components (C1, C2, C3) using parallel factor (PARAFAC) analysis. We compared the excitation and emission maxima of these components with the literature and correlated the PARAFAC components with each other and with fluorescence indices. The correlations suggest that two PARAFAC components are derived from allochthonous sources (C1, C3) and one is derived autochthonously (C2). The chromophoric DOM matrix was dominated by signals of humic-like substances with a highly complex structure, followed by humic-like, fulfic acids, low-molecular-weight substances, and with minor amounts of amino acids and proteins. The ratios of these PARAFAC components (C1 : C2, C1 : C3, C3 : C2) differed with respect to stream types (forestry versus non-forestry). We demonstrated a significant correlation between gross primary production (GPP) and signals of autochthonously derived, low-molecular-weight humic-like substances. A positive correlation between P / R (i.e. GPP/daily community respiration) and the fluorescence index FI suggests that the amount of autochthonously produced DOM increased overall with increasing GPP. In accordance with the coupling between DOM and the metabolism, our data also indicate that the composition of DOM is subject to seasonal fluctuations. We concluded that temporal and spatial differences in DOM composition are driven by whole-stream metabolism, in addition to pronounced effects coming from allochthonous sources.

scholarly journals Linkage between the temporal and spatial variability of dissolved organic matter and whole stream metabolism

2012 ◽  
Vol 9 (12) ◽  
pp. 18253-18293 ◽  
Author(s):  
S. Halbedel ◽  
O. Büttner ◽  
M. Weitere
Keyword(s):  
Molecular Weight ◽  
Land Use ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Primary Production ◽  
Gross Primary Production ◽  
Low Molecular Weight ◽  
Stream Metabolism ◽  
First Time ◽  
Dom Composition

Abstract. Dissolved organic matter (DOM) is an important resource for microbes, thus affecting the whole stream metabolism. The factors influencing its chemical composition and thereby also its bio-availability are complex and not thoroughly understood. We hypothesized that the whole stream metabolism itself can affect the DOM composition and that the coupling of both is influenced by seasonality and different land use forms. We tested this hypothesis in a comparative study on two pristine forestry streams and on two non-forestry streams. The investigated streams were located in the Harz Mountains (Central Europe, Germany). The whole stream metabolism was measured with a classical two station oxygen change technique and the variability of DOM with fluorescence spectroscopy. We take also into account the geochemical and geophysical characteristic of each stream. All streams were clearly net heterotrophic, whereby the non-forestry streams showed a higher primary production in general, which was correlated with irradiance and with the total phosphorus concentration. The whole stream metabolism but also the chromophoric DOM (CDOM) showed distinct seasonal patterns. We detected three CDOM component groups (C1, C2, C3) by the use of the parallel-factor-analysis (PARAFAC) and found temporarily variable, typical component fingerprints (C1:C2, C1:C3, C3:C2) for CDOM originated from forestry streams and from non-forestry streams. Based on comparative literature studies and correlation analysis with different indices, we demonstrate that two of the components are clearly from terrigenous sources (C1, C3) and one is rather autochthonously (C2) derived. The whole CDOM matrix was dominated by humic like, high molecular-weight substances, followed by humic like, fulfic acids, low molecular-weight substances, and with minor amounts of amino-acids and proteins. We showed for the first time a correlation between the gross primary production (GPP) and the autochthonously derived, low molecular weight DOM. The amount of autochthonously produced DOM increased overall with increasing GPP, as indicated by a tight, positive correlation between the fluorescence index (FI, R2 = 0.84) or C2 (R2= 0.48) and the ratio of GPP and the daily community respiration (CR24). This study showed for the first time the linkage between whole stream metabolism and DOM composition, based on a new integrated approach. We demonstrated that this relationship is influenced by seasonality and different land use forms. These complex mechanisms lead to typical DOM fingerprints for streams pass through the different land use forms.

Photoformation of Low-Molecular-Weight Organic Acids from Brown Water Dissolved Organic Matter

2003 ◽  
Vol 37 (18) ◽  
pp. 4190-4198 ◽  
Author(s):  
Thomas Brinkmann ◽  
Philip Hörsch ◽  
Daniel Sartorius ◽  
Fritz H. Frimmel
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Organic Acids ◽  
Low Molecular Weight

Effects of dissolved organic matter on sorption of benzotriazole to soil

2020 ◽  
Author(s):  
Lin Wu ◽  
Jin’e Dai ◽  
Erping Bi
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Organic Contaminants ◽  
Low Molecular Weight ◽  
Sorption Equilibrium ◽  
Solution Ph ◽  
Environmental Behaviors ◽  
Unsaturated Zones ◽  
Molecular Weight Fractions

<p>Dissolved organic matter (DOM) plays an important role in affecting the environmental behaviors of organic contaminants. Effects of two representative DOMs (dissolved humic acid (HA) and tannic acid (TA)) on sorption of benzotriazole (BTA) to a reference soil were investigated by batch experiments. The results indicated that TA had stronger sorption to soil than HA (initial solution pH=6.0±0.1). This is because that TA contains more carboxylic and phenolic groups than those of HA. In the solution with DOM, the enhanced sorption of BTA was caused by cumulative sorption resulting from sorbed DOM. Hydrogen bonding was proposed as the main binding mechanism between BTA and the sorbed DOM. When the solution pH at sorption equilibrium increased from 6.5 to 10.5, the electrostatic repulsion inhibited the sorption of BTA in solution with/without HA. In addition, less hydrogren bonds made the effect of HA in promoting BTA sorption decrease when solution pH changed from 6.5 to 10.5. Higher molecular weight fractions of HA could be preferentially sorbed by the soil, its enhancement on BTA sorption was more obvious than that of the low molecular weight fractions. These findings are conducive to a better understanding of environmental behaviors of BTA as well as other organic compounds with similar structure in the unsaturated zones.</p>

scholarly journals Sea cucumbers reduce chromophoric dissolved organic matter in aquaculture tanks

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4344 ◽  
Author(s):  
Seyed Mohammad Sadeghi-Nassaj ◽  
Teresa S. Catalá ◽  
Pedro A. Álvarez ◽  
Isabel Reche
Keyword(s):  
Water Quality ◽  
Molecular Weight ◽  
Time Series ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Chromophoric Dissolved Organic Matter ◽  
Low Molecular Weight ◽  
Optical Parameters ◽  
Absorption Coefficients ◽  
Sea Cucumbers

Background Mono-specific aquaculture effluents contain high concentrations of nutrients and organic matter, which affect negatively the water quality of the recipient ecosystems. A fundamental feature of water quality is its transparency. The fraction of dissolved organic matter that absorbs light is named chromophoric dissolved organic matter (CDOM). A sustainable alternative to mono-specific aquaculture is the multitrophic aquaculture that includes species trophically complementary named “extractive” species that uptake the waste byproducts. Sea cucumbers are recognized as efficient extractive species due to the consumption of particulate organic matter (POM). However, the effects of sea cucumbers on CDOM are still unknown. Methods During more than one year, we monitored CDOM in two big-volume tanks with different trophic structure. One of the tanks (−holothurian) only contained around 810 individuals of Anemonia sulcata, whereas the other tank (+holothurian) also included 90 individuals of Holothuria tubulosa and Holothuria forskali. We routinely analyzed CDOM absorption spectra and determined quantitative (absorption coefficients at 325 nm) and qualitative (spectral slopes) optical parameters in the inlet waters, within the tanks, and in their corresponding effluents. To confirm the time-series results, we also performed three experiments. Each experiment consisted of two treatments: +holothurians (+H) and –holothurians (−H). We set up three +H tanks with 80 individuals of A. sulcata and 10 individuals of H. tubulosa in each tank and four –H tanks that contained only 80 individuals of A. sulcata. Results In the time-series, absorption coefficients at 325 nm (a325) and spectral slopes from 275 to 295 nm (S275−295) were significantly lower in the effluent of the +holothurian tank (average: 0.33 m−1 and 16 µm−1, respectively) than in the effluent of the −holothurian tank (average: 0.69 m−1 and 34 µm−1, respectively), the former being similar to those found in the inlet waters (average: 0.32 m−1 and 22 µm−1, respectively). This reduction in the absorption of the dissolved organic matter appears to be mediated by the POM consumption by holothurians. The experiments confirmed the results observed in the time-series. The a325 and S275−295 values were significantly lower in the treatment with holothurians than in the treatment without holothurians indicating a reduction in the concentration of chromophoric organic compounds, particularly of low molecular weight. Discussion Consequently, sea cucumbers appear to improve water transparency in aquaculture tanks. The underlying mechanism of this improvement might be related to the POM consumption by holothurians, which reduces the concentration of CDOM derived from POM disaggregation or to the direct assimilation of dissolved compounds of low molecular weight as chromophoric amino acids.

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